In the areas of industrial production, pressure measurement, etc., on-site verification or calibration needs to be carried out on all the utilized pressure gauges, after used for a certain period of time, in order to determine whether a pressure gauge is accurate.
In conventional pressure calibration instruments, operation is carried out in a closed pressure calibration pipe, where gas pressure is generated through manual pressurization, and pressure instrument indications are read out by observation, and where the gas pressure is regulated in a manual pressurizing manner. The effect of the regulation is to provide, at a pressure output port, a certain accurate gas pressure as a standard pressure for access of pressure instruments to be calibrated, so as to perform calibration on various pressure instruments.
However, such a conventional pressure calibration manner involves human observation and manually operated pressure regulation, suffers from large observation errors, and is time and effort consuming. Especially in an industrial field or within a small pressure range, when performing pressure detection, manually adjusting pressure is not easily stabilized, observation is greatly affected by human disturbance factors, and working efficiency is quite low.
To solve this problem, increasing the working efficiency of pressure detection, in recent years, many companies have developed conventional pressure controllers. The pressure controller and an externally connected gas cylinder together form a device system. In a closed pressure calibration pipe, the gas cylinder provides a gas pressure according to a set pressure, and through automatic monitoring of a pressure sensor and automatic control of a pressure regulator, a set pressure output is provided for access of pressure instruments to be calibrated, so as to perform automatic calibration on the pressure instruments. This method overcomes the disadvantages of human observation and manually operated pressure regulation, can automatically monitor and adjust the pressure, and significantly improves the working efficiency.
Nonetheless, the conventional pressure controller is not portable due to its own large volume, the use of AC power supply for supplying power, large volume of the external gas cylinder, and place restriction on chemical gases within the cylinder, etc. For a large number of field used pressure instruments, there exists the disadvantage that calibration can not be implemented on-site.
As for a digital pressure instrument such as a pressure transducer, whether its output signal value is accurate or not directly affects the measured pressure thereof. Therefore, for such a digital pressure instrument, in addition to magnitude calibration for pressure of the instrument, magnitude calibration for electric signals (current, voltage, and switch pulse) thereof is also required. Among prior art full-automatic pressure calibration technologies, there is not yet a technology capable of integrating pressure calibration and electric signal calibration.
On the other hand, in prior art pressure controllers, typically one pressure sensor is used as a standard device and is incorporated in the instrument. In prior art pressure controllers, there are also cases of using two pressure sensors, where one is used as a pressure standard device, and the other is used to measure atmospheric pressure. In either case, the measuring range is a fixed single range, limiting pressure measurement and control range of the instrument. For some measuring ranges, unless another pressure controller with corresponding range is used, measurement accuracy will be affected by the measuring ranges. This requires a plurality of multi-range pressure controller devices at the time of pressure instrument calibration, causing inconvenience to on-site detection.